Structure Stability and Microwave Dielectric Properties of (1 − x ) Ba(Mg1/2 W1/2 ) O3 + x Ba(Y2/3 W1/3 )O3 Ceramics

Abstract

The structure stabilities of double perovskite ceramics- (1 − x) Ba(Mg1/2W1/2)O3 + xBa(Y2/3W1/3)O3 (0.01 ≤ x ≤ 0.4) have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Raman spectrometry in this study. The microwave dielectric properties of the ceramics were studied with a network analyzer at the frequency of about 8–11 GHz. The results showed that all the compounds exhibited face-centered cubic perovskite structure. Part of Y3+ and W6+ cations occupied 4a-site and the remaining Y3+ and Mg2+ distributed over 4b-site, respectively, and kept the B-site ratio 1:1 ordered. Local ordering of Y3+/Mg2+ on 4b-site and Y3+/W6+ cations on 4a-site within the short-range scale could be observed with increasing Y-doping content. The decomposition of the double perovskite compound at high temperature was successfully suppressed by doping with Y on B-site. However, Ba2Y0.667WO6 impurity phase appeared when x > 0.1. The optimized dielectric permittivity increased with the increase in Y doping. The optimized Q × f value was remarkably improved with small amount of Y doping (x ≤ 0.02) and reached a maximum value of about 160 000 GHz at x = 0.02 composition. Further increasing in Y doping led to the decrease in Q × f value. All compositions exhibited negative τf values. The absolute value of τf decreased with increasing Y-doping content. Excellent combined microwave dielectric properties with εr = 20, Q × f = 160 000 GHz, and τf = −21 ppm/°C could be obtained for x = 0.02 composition.